There are a variety of gas sensor constructions in which it is necessary to seal a member such as a pin or the like into a bore so as to prevent the passage of liquid or gas through the bore. O-rings have been used in the past to achieve such sealing both in cases where the components move relative to one another (such as described in U.S. Pat. No. 4,221,651) and in which they are relatively static. The present invention is concerned with a static arrangement of components.
The method of securing O-rings in a static sealing configuration recommended by manufacturers is to place the ring in a U-shaped recess extending around the bore so that the ring contacts the elongate member and the seal action is based on the ability of the seal to undergo axial or radial deformation of its cross-section. In order for the seal to function properly, manufacturers require that the size of the groove or channel is larger than the O-ring cross-section typically having a cross-sectional area more than 25% that of the O-ring so that the pressure can act on a relatively large part of the ring surface and so that there is sufficient space in the groove should any volume increase of the O-ring occur due to exposure to chemicals.
We have found, however, that some leakage of liquid still occurs in these configurations.